Abstract

The Catoche Tongue is a major reentrant in the Campeche Platform in the southeastern Gulf of Mexico (Figure 1, 1a). This feature extends about 125 km (77.6 mi) into the platform and varies in width from 25 to 100 km (15.5 to 62 mi). Bathymetric data indicate that the floor of the Tongue is a continuation of the Gulf of Mexico abyssal plain and that the steep margin of the Tongue is a continuation of the Campeche Escarpment which forms the outer margin of the Campeche Platform itself. The main questions about this feature are: (1) what is the mechanism of formation; (2) what is the age of formation; (3) do the margins of the Catoche Tongue consist of the same geologic section as the outer platform escarpment; and (4) what is the age and geology of the fill. Mechanism and margin similarities are interpreted in this paper by means of multichannel seismic data, and reason able suggestions are made as to age and lithology of fill by extrapolating published drilling results and regional geology.

Lower Cretaceous reef and fore-reef material have also been dredged from the escarpment (Bryant et al, 1969) and drilled along its base (Schlager, Buffler, et al, in press). A shallow-marine environment, then, appears to have existed over the entire Campeche Platform during Early Cretaceous time. It was a "great thickness of limestone and evaporites" which formed as the upper surface of these deposits remained essentially at sea level while their base subsided (Garrison and Martin, 1973). However, in Late Cretaceous time the outer platform foundered, possibly because of an acceleration of the subsidence postulated above (Worzel, Bryant et al, 1973; Antoine et al, 1974). The outer platform strata thereafter consisted of foraminiferal ooze and chalk (Worzel, Bryant et al, 1973).

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